What term describes the occurrence of PVCs that arise from different areas of the heart?

The term that describes the occurrence of premature ventricular contractions (PVCs) arising from different areas of the heart is "multifocal." This indicates that the PVCs originate from more than one ectopic focus within the ventricles. Each focus can have distinct electrical characteristics, which results in varying shapes on an electrocardiogram (ECG).

When PVCs are multifocal, the differing morphologies reflect the diverse locations in the heart's ventricular myocardium where the impulses are initiated. This can often be seen in patients with underlying heart disease or electrolyte imbalances, leading to variability in the PVC pattern.

In contrast, the other terms refer to different concepts. Monomorphic PVCs arise from a single ectopic focus and have a consistent appearance on an ECG. Unifocal means there is only one focus causing the PVCs, also resulting in a uniform shape. Sustained typically refers to tachyarrhythmias that persist over a longer duration, rather than the specific characteristics of PVCs. Thus, understanding the definition of multifocal PVCs clarifies their diverse origin and significance in cardiac function assessments.